Press-guard



W. J. PARKINSON.

PRESS GUARD. APPLICATION FILED NOV-21,1919.

1,394,501, Patented Oct. 18, 1921.

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INVENTOR,

WITNESSES my 771/. W BY U I l W ATTORNEYS.

UNITED STATES PATENT OFFICE.

WILLIAM J. PARKINSON, OF ROCHESTER, NEW YORK, ASSIGNOR TO EASTMAN KODAK COMPANY, OF ROCHESTER, NEVJ YORK, A CORPORATION OF NEW YORK.

PRESS-GUARD.

Specification of Letters Patent.

Patented Oct. 18, 1921.

Application filed November 21, 1919. Serial No. 339,751.

To all whom it may concern:

Be it known that I, lVILLiAM J. PARKIN- son, a citizen of the United States of America, residing at Rochester, in the county of Monroe and State of New York, have invented certain new and useful Improvements in Press-Guards, of which the following is a full, clear, and exact specification.

The present invention relates to safety appliances for machinery, and has for its oi ject to provide a simple, cheap and efficient guard for punch presses, which will eliminate a large number of serious accidents to the hands of punch press operators, due sometimes to the operators negligence, sometimes to worn and otherwise defective clutch mechanism, and sometimes to undue vibration and shaking of the working parts of the press guard. To these and other ends the invention consists in certain improvements and combinations of parts as will be hereinafter more fully described, the novel features being pointed out in the claims at the end of the specification.

This invention is an improvement over the punch press safety guard, disclosed in the application of Edmond De Maec-ker, Serial No. 323,963, filed Sept. 15, 1919.

In the drawings in which like reference characters designate like parts:

Figure 1 is a front elevation of punch press equipped with my improved safety guard;

Fig. 2 diagrammatically illustrates the position of the parts just as the guard wing return from swinging across the bed;

Fig. 3 is a plan view of the parts shown in Fig. 2.

My invention is applied, in this instance, to a punch press guard of the type shown in Patent No. 1,17 8,168, MacDonald & Dougherty, Apr. 4:, 1916, wherein guards swing across the front of a reciprocating mechanism to prevent the hands of the operator from being placed under the moving parts of the press during a predetermined interval of time. I will, therefore, describe such parts of the guard as pertain to a clear understanding of my invention. Punch press guards are usually designed to function before the ram descends, being actuated either by the foot treadle, or by the ram itself,

there being some types, such as the Mac- Donald et al. type, wherein two guards are operated, one through the foot treadle and the other through the ram. It frequently happens, particularly in the type where the press is operated through a foot treadle, that the rebound of the wing guards and their operative parts will cause a second actuation of the press, and the operator being caught oif his guard is injured. The danger, therefore, lies in not holding the safety guards in their inoperative position, until the vibration of the parts entirely cease, and since theinterval of time during which the guard is inoperative is very short, it is difficult to provide a satisfactory apparatus to overcome this fault. The vibration in large punch presses and in small rapidly operated presses is excessive because of the necessarily comparatively loose connection between theirworking parts, as, for instance, is the case with the foot treadle. Generally the operator can depress this member over six inches before the press is operated. My invention is directed particularly to correcting this shock and jar to the guard and press mechanism, and substitutes for the rather complicated locking device controlled through the foot treadle and latch mechanism of the before mentioned application of De Maecker, a very simple and inexpensive shock absorber which operates without complicated springs and latches.

, Referring to the drawings, a frame 1, suports a table 2, and an upper frame 3.

hrame 3 has a way 4 in which a plunger 5 slides, being moved by an eccentric 6 operated by shaft 7. Power is applied to the fly wheel 8 which normally turns loosely on shaft 7, there being a clutch 9 for keying the shaft to the flywheel 8. For actuating clutch 9 a shaft 10 extends up from a foot treadle 11, and in this instance is adjusted so that the clutch 9 is operated at the end of the downward movement of foot treadle 11 causing the wheel 8 and shaft 7 to rotate together for one revolution and then to automatically throw out the clutch.

A yoke 12 attached to the upperframe 3 supports the safety mechanism, which consists of a safety guard or wing 13 attached to a shaft 14: which in turn is rotatably mounted on yoke 12 by means of a casting 15 in which there is a bearing for stub shaft 17 fastened in yoke 12. The wing 13 is made of celluloid for convenience, although wire mesh or other material may be used if desired. Casting 15 is attached to the short arm 20 of a bell orank'lever 18 through a link 19, the long arm 21 of the bell crank lever being connected by links 22 and 23 to a lever 24 pivoted to the frame 3 at 25. On lever 24 is pivotally attached the upper end of a rod 26, the lower end of which 27 is attached to a shaft 28 carried by the foot lever 11. If desired a second set of parts for operating wing 13 by the ram can be attached to the guard 13 or to a second guard, but for the purpose of illustration of my invention the above described mechanism is sufficient.

The guard 13 is operated in the following manner: work is placed on the female die 30 on table 2, the male die 31 being ahixed to plunger 5. The operator having his work in place depresses foot lever 11 slowly. After the foot lever 11 is lowered a portion, say one-quarter of the movement,'the rod 26 draws down lever 24;, which through links 22 and 23 pull down arm 21 of bell crank lever 18, thus thrusting arm 20 toward the ram so that link 19 will, by thrusting to the left, cause the casting 15 to revolve about shaft 17 in a counter clockwise direction, thereby turning wing 13 so as to cross the path through which work was placed on the bed 2. If the operators hands had not previously been removed, the wing 18 would remove them by thrusting them from the table 2. By continuing the depression of treadle 11, clutch 9 operated by rod 10 keys shaft 7 and fly wheel 8 together for a revolution, thus causing ram 5 to function and perform an operation on the work. Upon releasing the pressure on treadle 11, the parts all re turn to their inoperative position, and since forming presses operating at a moderate speed frequently function from forty to sixty times a minute, and simple blanking machines operating much more rapidly, from two to five times a second, it can be readily seen that these movements are rapid and a jerk and jar of considerable magni tude results when the parts are momentarily brought to rest.

I overcome this difficulty by mounting a weight 40, which in this case is cast so as to form a lever, having a bearing 12 to revolve about a stub shaft 13 attached to the yoke 12. This weighted lever rests normally on a stop pin 14, and its'movement is limited by a second stop or pin 45, also fastened to yoke 12. To the casting 15, I fasten an arm 16 at such an angle that a large part of the surface 47 on the under side of weight 40 will contact with the lever or arm 4L6 when it is at rest as shown in Fig. 1. As the wing flies back after an actuation, the arm at strikes ing with the wing 13. In other words, the

tendency of the wing guard is, where no shock absorber is provided, to return from its movement across the bed and stop with a jerk, vibrating back and forth from its normal inoperative position, which is shown in Fig. 1, because of the play between the various links, levers, etc. Butthis ar in the embodiment of my invention shown in the drawings, is transferred from the wing and wing operating mechanism to the lever weight 40, leaving the wing 13 practically still. After the impact of arm 16 with weight 40 pin 44 if necessary limits the upward movement of the weight. I prefer to design my machine so that the weight40 will normally rotate only to the degree shown in Fig. 2. In returning, pin 4E5 stops the weighted-lever 40 in its normal position. As will be seen from Fig. 1, when arm 46 strikes the weight, the leverage of arm 46 is much less than it is after the weight 10 starts to rotate, as in Fig. 2, but after the first impact, the force exerted by the various parts on lever 46 is considerably less, so that the advantage in leverage is offset by the reduced force. Moreover it should also be noted that the weight lever 40 is designed so that the arm46 by rocking'a comparatively slight distance will rotate the weight a muc greater amount than would be the case if the levers were of equal length, and yet the first jar is received by weight 10 when its mechanical advantage is at its greatest because the entire under surface 47 contacts with arm 46. This condition is desirable because it reduces the movement of the parts, to a minimum without decreasing the effec' tiveness of the shock absorber.

Having thus described my invention, what I claim as new and desire to obtain by Letters Patent is: V

1. In a safety. guard for punch presses, the combination of a bed, a frame and a ram movable in the frame with a safety guard,

operating mechanism for the safety guard movable in the frame with a safety guard,

operating mechanism for the safety guard adapted to move said guard across the bed and back at each actuation of the ram, a lever for contacting with a part of the safety guard when'the same is at rest, said lever being pivoted to the frame and consisting of a weight, means on the frame for limiting the movement of the lever, said weighted lever receiving the shock transmitted from tlie'safety' guard upon its return from an actuation, thereby preventing vibration of the safety guard. l

3. In a safety guard for punch presses, the combination of a bed, a frame and a ram movable over the bed with a swinging safety wing, means for moving the safety wing, an arm attached to the safety wing and a lever attached to the frame, the arm being adapted to contact with a lever when the safety wing is at rest, the lever alone preventing the rebound of the safety wing as it comes to rest.

4;, In a safety guard for punch presses, the combination of a bed, a frame and a ram movable over the bed with a swinging safety wing, means for moving the safety wing, an arm attached to the safety wing, a weighted lever pivoted to the frame, said wing arm and said lever being in contact when the wing guard is at rest, the weighted lever receiving the shock or vibration from the wing arm as the wing guard comes to rest.

5. In a safety guard for punch presses, the combination of a bed, a frame and a ram movable over the bed with a swinging safety wing, means for moving the safety wing, an arm attached to the safety wing, a weighted lever pivoted to the frame, stops on the frame to limit the movement of the weighted lever, the wing arm striking the lever and passing thereto the shock resulting from the wing guard coming to rest after an actuation, and the stop preventing the weighted lever from returning the shock to the wing guard.

6. In a safety device for punch presses, the combination of a bed, a ram, and ram moving mechanism with a safety guard adapted to cross a side of the bed, an arm fastened to the safety guard and a weight pivoted to the frame, the said arm and lever being positioned so as to give the weight the mechanical advantage when a force is first exerted by the arm on the lever, and then to give the arm the mechanical advantage over the weight as the force is further exerted, so that the weight will sustain the for holding the lever in a predetermined position, said arm striking said lever as the wing guard returns from an actuation, the wing guard and arm being rotated beyond their normal position of rest, the said lever receiving the resulting vibration of the wing guard.

8. In a punch press safety device, the combination of a frame, a bed, a ram intermittently operating over the bed with a wing guard pivoted to the frame, mechanism for moving the guard in timed relation to the ram, an arm attached to the guard, and a lever pivot-ed to the frame, the arm tending to rock the lever when the wing guard swings past its position of rest in one direction.

9. In a punch press safety device, the combination of a frame, a bed, a ram intermittently operating over the bed with a wing guard pivoted to the frame, mechanism for moving the guard in timed relation to the ram, an arm attached to the guard, and a lever pivoted to the frame, the arm tending to rock the lever when the wing guard swings past its position of rest in one direction, said lever limiting the movement of the wing guard as it comes to rest.

10. In a punch press safety device, the combination of a frame, a bed, a ram intermittently operating over the bed with a wing guard pivoted to the frame, mechanism for moving the guard in timed relation to the ram, an arm attached to the guard, and a lever pivoted to the frame, the lever having a flat surface contacting with the arm tending to normally hold the arm and thereby the wing guard steady in its inoperative position.

11. In a punch press safety device, the

combination of a frame, a bed, a ram intermittently operating over the bed with a wing guard pivoted to the frame, mechanism. for moving the guard in timed relation to the ram, an arm attached to the guard, and a lever pivoted to the frame, the lever having a fiat surface contacting with the arm tending to normally hold the arm and thereby the wing guard steady in its inoperative position, and to absorb the shock resulting from the wing guaxd suddenly coming to rest, preventing the wing guard from oscillating back and forth from its inoperative position.

12. In a punch press guard, the combination of a frame, a ram and ram operating mechanism with a swinging wing guard, a foot treadle for operating the ram operating mechanism, and means for swinging the wing guard controlled by the foot treadle, and a weight pivoted to the frame so as to be struck by the wing guard at one end of its swing, the vibration of the wing guard being taken by the weight, so that the jar and back lash of the wing guard cannot react through the foottreadle to the ram operating mechanism, causing accidental tripping of the ram.

13. In a punch press guard, the combinationof a, press comprising a frame, a bed, a ram movable in the frame With a safety guard pivoted to the frame and adapted to cross aside or" the bed when the ram is moved, a mechanism for moving the wing guard and means, independent of the 10 guard operating mechanism, for absorbing I the vibration of the returning safety guard comprising a Weight on the end of a, lever.

Signed at Rochester, New York, this 18th day of November, 1919.

WILLIAM J. PARKINSON. 

